MATCHING PURSUIT IN ADAPTIVE DICTIONARIES FOR SCALABLE AUDIO CODING
Emmanuel Ravelli, Laurent Daudet, Telecom Paristech · 2008
In previous work [10], we have proposed a new signal repre-sentation for audio coding, where the signal is decomposed in a union of MDCT bases using matching pursuit. The re-sulting coder gave better performance than a transform coder at low bitrates but slightly worse at high bitrates. In this pa-per, we propose an adaptive matching pursuit algorithm that in the first iterations decomposes the signal into the redun-dant union of MDCT bases, and then, when the residual en-ergy decay becomes too low, switches to an orthogonal basis (one of the MDCT bases). We investigate simple strategies to determine in which iteration switching is near-optimal in terms of rate-distortion. We present in this paper a prototype audio coder based on this algorithm, that reaches the perfor-mance of the previous approach at low bitrates and the one of transform coding at high bit rates. 1.